Google reached out to developers at its annual I/O event in San Francisco Wednesday during the conference-opening keynote session with a spate of announcements that included a new version of its Android mobile operating system, a new Google-branded tablet, its first fully home-grown piece of hardware, and a spectacular demonstration of the potential of Project Glass.

Hugo Barra, Google product manager and director of the company's Android group, unveiled Android 4.1, code-named "Jelly Bean." An incremental improvement of "Ice Cream Sandwich" (Android 4.0), the new OS fairly bristles with new features, including voice search, voice typing, a predictive keyboard, and support for richer, more complex notifications (including the ability to allow developers to craft custom notifications for their applications). The OS also comes with "Google Now," a predictive search engine for the Android phone designed to provide users with information "it thinks you need." It could, for example, display a menu from a restaurant a user just walked into, or suggest alternate driving routes because of backed up traffic.

Barra demoed the OS's improved speed and smooth graphics, the development of which was dubbed internally "Project Butter." Among the improvements: a more elastic home screen that supports resizable widgets that automatically reorganize the screen around them. The new OS, Barra said, is an example of his company "making things simple, beautiful, and really smart."

The search giant also unveiled a new seven-inch, Android-based tablet, the Nexus 7. Manufactured by Asus, the tablet is 10.45 mm thick, weighs 0.7 pounds, and is the first device to use Google's Chrome browser by default. The tablet is available now from the Google Play store starting at $199 for the 8GB version, and $249 for the 16GB version. Customers who buy the device from Google Play will receive a $25 credit to spend on Google Play media. The Nexus 7 will begin shipping in mid-July, the company says.

Google also debuted its first fully home-grown hardware: the Nexus Q, a small, Android-powered media player. The spherical, 4.6-inch diameter device is designed to plug into speakers and television sets in the home and stream songs and videos stored in the cloud or from an Android phone. It also streams YouTube videos. Barra called it "the first ever social streaming device," because of its ability to allow friends to create collaborative playlists. He said that Google is encouraging the "general hackability" of the device, so that "developers can create unique experiences."

The company spent a lot of time during the conference keynote opener on updates of its evolving social network, Google+, including a new Google+ app for both the Android OS and Apple's iOS. Vic Gundotra, the company's senior vice president of social business, demoed a number of Google+ features, including Google Hangouts improvements and a new invites feature, Google Events.

In what some tweeters described as a Steve Jobs-like appearance, Google co-founder Sergey Brin interrupted Gundotra's demoes to promote Project Glass, the company's nascent head-mounted computer "glasses." The devices are designed to allow users to receive texts, emails, music, weather reports, and other input via a tiny screen positioned slightly above one eye.

In a truly splashy display of the potential of this device, Brin displayed a live Hangout session that included input from Glass-wearing skydivers, who jumped from a blimp over the Moscone Center and landed on the roof, handed off a package to stunt BMX bikers (also wearing the Google glasses), who jumped to another roof and passed the package to another glasses wearer, who rappelled down the building to the street and handed the package off to another Glass-wearing biker, who rode into the auditorium and delivered the package to Brin (and thunderous applause).

Brin appealed to the developers in the audience to begin participate in Project Glass, and said that, although the technology isn't yet available in the U.S., conference attendees who are based here would be allowed to pre-order the Explorer Edition immediately. The price: $1,500. This very early version of the technology is expected to ship sometime early next year.

More than 6,000 attendees are expected to attend the three-day event. All attendees will be getting new Android phones, Nexus 7 tablets and Nexus Q devices, compliments of Google. Google started what has become a tradition of seeding the developer community with Android-based hardware by handing out Android phones at the first Google I/O event in 2008.